Nanosuspensions of photographically useful compounds are becoming increasingly prevalent in the photographic industry. Processes that produce submicron solid particle colloids have found advantageous use in producing dispersions of photographically useful compounds such as filter dyes, sensitizing dyes, etc. U.S Pat. Nos. 4,294,916 and 4,294,917 to Postle et al. describe solid particle dispersions of photographic filter dyes and point out that such solid particle dispersions provide broad spectral absorptions. The preparation and use of solid particle dispersions of sensitizing dyes are disclosed in German Patent No. 1,547,705. Milling processes for producing solid particle dispersions using sand, bead, dyno, and Masap mills, and using mills described in U.S. Pat. Nos. 2,581,414 and 2,855,156 are disclosed in British Patent No. 1,570,362. The British patent discloses that non-diffusing, slightly soluble color couplers can be dispersed as solid particle dispersions. Development inhibitor releasing (DIR) couplers, spectral sensitizing dyes, and photographic stabilizers are also disclosed in this British patent as being dispersed as solid particle dispersions.
The art of precipitation of organic substances having relatively low water solubility, starting from a solution state to a stable fine particle colloidal dispersion is known. Such precipitation is generally achieved by dissolving the substance in a water-miscible solvent aided by addition of base to ionize the substance, addition of a dispersing aid with subsequent precipitation of the substance by lowering pH or by shifting the concentration of two or miscible solvents such that the substance is no longer soluble in the continuous phase and precipitates as a colloidal dispersion or slurry.
Townsley et al., in U.K. Pat. No. 1,193,349, disclose a process whereby a color coupler is dissolved in a mixture of water-miscible organic solvent and aqueous alkali. The coupler solution is then mixed with an aqueous acid and a protective colloid, to form a dispersion of the color coupler by pH shift. Such a dispersion can be mixed with an aqueous silver halide emulsion and coated on a support, and incorporated into a photographic element.
Langen et al., in U.K. Pat. No. 1,570,362 disclose the use of solid particle milling methods such as sand milling, bead milling, dyno milling, and related media, ball, and roller milling methods for the production of solid particle dispersions of photographic additives such as couplers, UV-absorbers, UV stabilizers, white toners, stabilizers, and sensitizing dyes.
Henzel and Zengerle, in U.S. Pat. No. 4,927,744, disclose photographic elements comprising solid particle dispersions of oxidized developer scavengers. Said dispersions are prepared by precipitation and by milling techniques such as ball-milling.
Boyer and Caridi, in U.S. Pat. No. 3,676,147, disclose a method of ball-milling sensitizing dyes in organic liquids as a means of spectrally sensitizing silver halide emulsions. Langen et al., in Canadian Patent No. 1,105,761, disclose the use of solid particle milling methods and processes for the introduction of sensitizing dyes and stabilizers in aqueous silver salt emulsions.
Swank and Waack, in U.S. Pat. No. 4,006,025, disclose a process for dispersing sensitizing dyes, wherein said process comprises the steps of mixing the dye particles with water to form a slurry and then milling said slurry at an elevated temperature in the presence of a surfactant to form finely divided particles. Onishi et al., in U.S. Pat. No. 4,474,872, disclose a mechanical grinding method for dispersing certain sensitizing dyes in water without the aid of a dispersing agent or wetting agent. This method relies on pH control in the range of 6-9 and temperature control in the range of 60.degree.-80.degree. C.
Moelants and Depoorter, in U.S. Pat. No. 4,266,014, Lemahieu et al., in U.S. Pat. No. 4,288,534, Postle and Psaila, in U.S. Pat. Nos. 4,294,916 and 4,294,917, 1981, Anderson and Kalenda, in U.S. Pat. No. 4,357,412, Ailliet et al., in U.S. Pat. No. 4,770,984, Factor and Diehl, in U.S. Pat. No. 4,855,221, Diehl and Reed, in U.S. Pat. No. 4,877,721, Dickerson et al., in U.S. Pat. No. 4,900,652, Factor and Diehl, in U.S. Pat. No. 4,900,653, Schmidt and Roca, in U.S. Pat. No. 4,904,565, Shuttleworth et al., in U.S. Pat. No. 4,923,788, Diehl and Factor, in U.S. Pat. No. 4,940,654, Diehl and Factor, in U.S. Pat. No. 4,948,717, Factor and Diehl, in U.S. Pat. No. 4,948,718, Diehl and Brown, in U.S. Pat. No. 4,994,356, disclose filter dyes and solid particle dispersions of dyes for use as filter dyes in photographic elements. They disclose that such dyes can be dispersed as solid particle dispersions by precipitating or reprecipitating (solvent or pH shifting), by ball-milling, by sand-milling, or by colloid-milling in the presence of a dispersing agent. Photographic elements containing such filter dyes and dispersions thereof are disclosed.
Komamura, in unexamined Japanese Kokai No. Sho 62[1987]-136645, discloses solid particle dispersions of heat solvent, wherein said heat solvent has a melting point of 130.degree. C. or greater. These heat solvent dispersions are incorporated in a thermally developed photosensitive material incorporating silver halide, a reducing agent, and a binder on a support, wherein said material obtains improved storage stability.
Chari et al., in U.S. Pat. No. 5,008,179, discloses methods for forming dispersions of photographic couplers, wherein aqueous dispersions of photographic coupler and of activating permanent solvent are combined and mixed with silver halide emulsion. Czekai and Bishop, in U.S. Pat. No. 5,110,717, disclose a process for making amorphous coupler dispersions from solid particle microcrystalline dispersions.
Texter et al., in U.S. Pat. No. 5,240,821, disclose solid particle dispersions of developer precursors, and photographic elements containing such dispersions. Texter, in U.S. Pat. No. 5,274,109, discloses microprecipitated methine oxonol filter dye dispersions. These dispersions are prepared with close attention paid to the stoichiometric amounts of acid used in the microprecipitation process.
Texter, in U.S. Pat. No. 5,360,695, discloses solid particle thermal solvent dispersions and aqueous developable dye diffusion transfer elements containing them. Texter, in U.S. Pat. No. 5,401,623, discloses nanoparticulate microcrystalline coupler dispersions wetted with coupler solvent. Texter, in U.S. Ser. No. 08/125,990 filed Sep. 23, 1993, discloses solid particle coupler dispersions for use in color diffusion transfer element.
U.S. Pat. No. 2,796,294 discloses in FIGS. 1 and 2 therein, container designs. U.S. Pat. No. 3,176,883 discloses in FIG. 1 therein an axisymmetric container design that has a bottom portion of greater diameter than the body portion, and wherein the diameter of said body portion increases steadily from the top of said body portion to where the body portion meets the bottom portion. U.S. Pat. No. 3,200,995 discloses in FIG. 1 therein a container design. U.S. Pat. No. 3,323,689 discloses in FIG. 3 therein a container design. U.S. Pat. No. 3,363,808 discloses, in FIGS. 1 and 9 therein, container designs. An airspace type spray dispenser for dispensing liquids in spray form is disclosed in U.S. Pat. No. 4,087,023. A squeeze bottle for dispensing a dry powder is disclosed in U.S. Pat. No. 4,091,966. When the bottle is inverted, the construction is such that a carrier stream of air, when the bottle is squeezed, is discharged through a fed stream of the powder. A right-angle spray nozzle for a squeeze bottle is disclosed in U.S. Pat. No. 4,415,122.
Traditionally, blown plastic bottles are processed in a manner which attempts to optimize strength and integrity of the container by various means of arranging the polymer molecules. An amorphous thermoplastic parison made of the crystallizable thermoplastics such as polyesters may be mechanically stressed at temperatures between the glass transition temperature and the melting point of the material, and then rapidly cooled to align the molecular structure and achieve high strength in the direction of molecular orientation. It is known in the prior art to injection mold a plastic parison having a localized thickened region which reinforces the heel of a blown bottle, as disclosed by Makowskyin U.S. Pat. No. 3,137,748.
Containers with internal rib structures are known in the art. Donnelly, in U.S. Pat. No. 3,114,932, teaches to extrude a tubular plastic parison having external reinforcing ribs which are reversed during the blow molding process to provide internal reinforcement to a blown container. Stena and Smith, in U.S. Pat. No. 4,912,048, disclose a bottle shaped culture vessel with fluted body wall providing internal ribbing. This internal ribbing provides increased internal surface area for the anchorage of cells and also provides enhanced agitation for the dispersal of cells, where improved dispersal and increased anchorage promote cell growth. U.S. Pat. No. 4,024,975 discloses a blow molded thin walled bottle with local internal ribbing formed by reversal of external ribs on a preform. Krishnakumar et al., in U.S. Pat. No. 4,977,005, Procock et al., in U.S. Pat. No. 4,525,401, and KriShnakumar et al. in U.S. Pat. No. 4,334,627, disclose a ribbed preform for forming a plastic container by blow molding. This preform is used to produce a bottle with a bottom reinforced with internal radiating ribs. Mahajan, in U.S. Pat. No. 4,403,706, discloses an improved preform for blow molding a plastic container having a "champagne bottle style" base, wherein tubular, hollow ribs for stiffening the bottom of the container are taught.
Methods for forming bottles and containers by various plastics molding operations are known in the art. Stenger, in U.S. Pat. No. 5,126,177, discloses a blow molding preform for a bottle with reinforcing ribs. This preform comprises angularly spaced ribs on a frusto-conical surface that are converted to internal ribs by molding a polyethylene terephthalate bottle. Japanese Publication No. 78-18504 discloses a hollow plastic article having internal ribs, whereby molten resin is injected into a molding cavity through a flow control ring having projections. These projections comprise inwardly projected obstructions on the walls of the ring so that the molten resin has a corresponding cross-section when it is injected into the molding cavity. Lee, in U.S. Pat. No. 4,151,249, discloses a method of making blown plastic bottles with at least one internal rib. Uhlig, in U.S. Pat. No. 3,956,441, discloses a method of making blown bottles having interior ribbed surfaces. Uhlig teaches to preblow a parison into a pre-blow mold having concave grooves patterned within its cavity walls, thereby forming an intermediate article with external ribs, and then finally blowing the intermediate article within a blow mold such that the bulbous ribs are inverted to form internal ribs.
The particulates in nanoparticulate suspensions typically have a density greater than the continuous phase of the nanoparticulate suspensions. As time passes, these particulates settle to form sediment that must be redispersed in order to obtain the expected concentration of suspended particulate in the suspension as a whole.
This sediment is the cause of previously unrecognized problems encountered when such suspensions are formed into light-sensitive coating compositions and elements. Densely packed sediments may in part break up upon shaking or mixing, but cause numerous large flocs of photographically useful nanoparticulates to persist in suspension, even after vigorous mixing. Such large flocs can cause significant coating defects when coating compositions comprising such flocs are applied in the formation of multilayer light-sensitive elements. Such large flocs can cause significant and unwanted light scattering in light-sensitive elements formed therefrom, and such light scattering can result in halation, speed loss, unwanted turbidity and loss of gloss, and color imbalance, as well as other unwanted and deleterious effects. When the photographically useful compound of such nanoparticulate suspensions is a key sensitizing compound, such as a sensitizing dye, a chemical sensitizing agent, or an organic-sulfur-based ripening agent, the resulting photographic speed of the light-sensitive element obtained may suffer a significant speed loss if the activity and concentration of sensitizing compound is too low in the suspension used. When nanoparticulate suspensions of such sensitizing compounds form dense sediment upon storage, they typically will not reconstitute upon shaking, stirring, or agitation, to completely disperse all of the sediment formed, and the resulting suspension is too low in concentration with respect to the sensitizing compound suspended therein.